Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless communication network may include a number of base stations (e.g., eNodeBs) that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via the downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.
In multiple connectivity wireless communications, the UE can be configured to communicate with multiple cells or cell groups configured by multiple base stations using multiple links. In addition, in an example, each of the links may be configured with multiple component carriers (e.g., carrier aggregation over one or more of the multiple links with the corresponding cell group). In this configuration, the multiple cells or cell groups may each utilize different frame structures (e.g., frequency division duplexing (FDD), time division duplexing (TDD), etc.), different subframe configurations (e.g., in TDD), technologies allowing for dynamic subframe configurations, asynchronous timing, etc., in communicating with the UE.
UEs can report power headroom to a cell in one or more subframes. Where power headroom reporting is to occur for the multiple cells or cell groups, it is possible that subframes over which the UE is configured to provide power headroom reports (in an uplink subframe) for one cell or cell group may be a downlink subframe or other non-uplink subframe (e.g., special subframe) for one of the other cells or cell groups. The reporting of the power headroom in such subframes may be undefined. Moreover, it is possible that actual power headroom can be reported for one cell group, but only reporting of virtual power headroom is possible for another cell group. Thus, techniques for reporting power headroom in multiple connectivity wireless communication are needed.